The very early time electromagnetic (VETEM) system: First field test results

The very early time electromagnetic (VETEM) system is a time-domain, surface-deployed system that has potential applications to direct detection of non-aqueous phase liquids as well as to the detection of buried objects. It is designed to operate in environments that are too conductive for ground penetrating radar (GPR) to be effective, and too shallow for standard electromagnetic systems. The VETEM system is a faster profiling complement to the frequency-domain high frequency sounder (HFS). First field tests of the VETEM were made at the Geophysics Performance Evaluation Range at Rabbit Valley west of Grand Junction, Colorado in June and July, 1995. A number of well defined targets of various types are buried there (Alien, 1995). The VETEM system was next used as part of the Electromagnetics Integrated Demonstation (EMID) at the Cold Test Pit at the Idaho National Engineering Laboratory (INEL) in November, 1995. The Cold Test Pit has a number of subareas with buried objects of various types. For the EMID tests, VETEM was run over three gridded areas: the Primary Grid (PG), the Large Object Pit (LOP), and the Calibration Cell (CC). In this paper we display recorded lines from the LOP that show VETEM is responding to electrical properties of the near surface and to buried objects.